Subway elv systems used in subway station, car depot, parking lot, the control center and other places, including communications, signal, comprehensive monitoring, power monitoring PSCADA, environment and equipment monitoring BAS, automatic fire alarm FAS, entrance guard ACS), AFC PIS, passenger information system of automatic fare collection system, platform screen door, substation dc operation, emergency lighting and other parts, system generally consists of computer, network equipment and automation control equipment, electricity load for level, thus requiring high reliability of back-up power for uninterrupted power supply, to ensure the quality of power supply and power supply continuity. Shielding door drive motor, substation DC operation and some of the communications equipment respectively using DC110V, DC220V and DC - 48 v power supply, generally by a special independent power supply DC power supply. Emergency lighting is commonly ac induction load, distribution within the scope of the entire station, some more noodles wide, with EPS power supply. The rest of the communication, signal and power monitoring, environment and equipment monitoring, access control, fire alarm, automatic fare collection, passenger information, such as shielding door network control system for computer and network equipment such as capacitive load, need AC380/220 v power supply, the most suitable UPS system for power supply. Due to the particularity of subway operation environment and its equipment, generally required to provide power supply of UPS system meet the following requirements: 1. The reliability is strong, can adapt to the underground environment, so as to ensure the station all elv systems equipment, stable and reliable operation; 2. Green environmental protection, electric power environment and the natural environment to avoid pollution; 3. High safety, protect the comprehensive, is not easy to cause equipment failure, do not threaten the personal safety; 4. Easy to close, remote management, has a standard communication interface and open communication protocol; 5. Try to adopt the centralized power supply, comprehensive use of various resources. At present, the integration of rail transit UPS power is a developing trend, new subway lines across the country are working in integrating UPS, because it is more advantageous to comprehensive utilization of resources, more conducive to professional maintenance and management, as well as to save room usable floor area.

According to the specific requirements of subway environment on the UPS system, we choose from in the NT series UPS (12 p), reached the dentsu DCF126 series accumulator and attain the dentsu intelligent power distribution cabinet group into the double power input and double bus architecture, Shared the battery pack, load combination of centralized power supply scheme of time-sharing power supply.

System of two UPS capacity is equal, mutual backup, each other through two redundant communication lines connected to each other, make them phase synchronization, always ensure that the back of the STS switch smoothly.

1, reliability, adapt to the underground environment. Such as UPS and heat-resistant, wide range of humidity, and the anti interference ability, wide range of input power supply voltage and frequency, and high output power quality, full bridge inverter, isolation transformer on load adaptability is strong, internal important line redundancy backup, fault tolerant ability, stand-alone MTBF of up to 300000 hours, etc. The double bus architecture has double protection to load.

2, UPS, low harmonic, high efficiency, low radiation, low noise characteristics reflected the green environmental protection, the characteristics of low power environment and the natural environment pollution.

3, UPS compliance with the safety standards of CE, TUV, IEC, etc, with the warm, overload, short circuit, wrong operation, battery protection functions such as the dead of night, and nearly, emergency shutdown function, on the far side of safe and reliable, not easily man-made equipment failure and safety threat.

4, UPS is equipped with a large Chinese/English graphical LCD display, as well as RS232, RS485, 20 selected 6 intelligent dry contact and for the choose and buy of SNMP, MODBUS card, etc., and has an open communication protocol provides, facilitate nearly, the remote monitoring management. For this solution can be UPS monitoring into the comprehensive monitoring system (ISCS), and the comprehensive monitoring system FEP interface, realize unified monitoring management of power supply.

5, the scheme at each site configuration of a powerful centralized power supply, UPS can make comprehensive utilization of load power resources. At the same time, share the battery pack and time-sharing power supply mode is a concrete embodiment of comprehensive utilization of resources.

The UPS for the load of centralized power supply table shows that the station, car depot and parking lot and the load control center in the order: 126 kva, 103 kva, 74 kva and 126 kva. These loads are computer and general input power factor is 0.7, 0.8, less than the output of the UPS power factor when selecting UPS capacity shall be calculated according to the VA value. UPS in order to ensure the long term run safely and reliably, the load is generally set at 60% ~ 80% of the rated capacity of UPS. So station, car depot and parking lot and control center should be configuration and 160 kva, 160 kva, 160 kva, 160 kva UPS, their capacity to achieve a single largest UPS of 78%, 64%, 74% and 78%, in line with the requirements of system reliability.

Sharing this scheme adopts the UPS battery solutions and mains stopped after the time-sharing power supply to load. In the station, for example: there are 40 kva load reserve 2 hours, 46 kva load reserve 1 hour, 40 kva reserve load 0.5 hours.

Based on the discharge characteristics of battery, if using the points and time (vertical) calculation method, the result will be larger than the actual configuration of the partial; If the power section (horizontal) calculation method, the result will be smaller than the actual configuration. Here the power section (level) calculation method to calculate, then modify the results. Calculation process is as follows:

P (W) batteries provide total power P (VA) load nominal capacity (VA)

Eta UPS inverter conversion efficiency Pf load input power factor

Pnc each battery only need to provide the power of the n number configuration of UPS battery

N of the single battery cell number

P = {P (VA) (W) x Pf} / eta

Pnc = P (W)/(n * n)

P (VA) = 40 kva Pf material load input power factor of 0.7

Inverter efficiency eta = 0.95 n = 29

N = 6

P = {P (VA) (W) x Pf} / eta

40000 x 0.7 = {} / 0.95

= 29473.68 (W)

Pnc = P (W)/(n * n)

= 29473.68 / (29 (6)

= 169.39 (W)

According to the constant power of battery discharge characteristics can be concluded that 2 hours discharge time, cut off voltage of 1.75 V, DC 12 V / 100 ah type of battery can provide power, 68.4 W group 169.39/68.4 = 2.48.

P (VA) = 46 kva Pf material load input power factor of 0.7

Inverter efficiency eta = 0.95 n = 29

N = 6

P = {P (VA) (W) x Pf} / eta

46000 x 0.7 = {} / 0.95

= 33894.74 (W)

Pnc = P (W)/(n * n)

= 33894.74 / (29 (6)

= 194.80 (W)

According to the constant power of battery discharge characteristics can be concluded that discharge time 1 hour, 1.75 V voltages, DCF126-12/100 type of battery can provide power, 112.2 W group 194.80/112.2 = 1.74.

3, 0.5 hours 40 kva:

P (VA) = 40 kva Pf material load input power factor of 0.7

Inverter efficiency eta = 0.95 n = 29

N = 6

P = {P (VA) (W) x Pf} / eta

40000 x 0.7 = {} / 0.95

= 29473.68 (W)

Pnc = P (W)/(n * n)

= 29473.68 / (29 (6)

= 169.39 (W)

According to the constant power of the battery can reach 0.5 hours discharge time, discharge characteristics under the cut-off voltage of 1.75 V, DC 12 V / 100 ah type of battery can provide power, 181.3 W group 169.39/181.3 = 0.93.

2.48 + 1.74 + 0.93 = 5.15 (group)

Due to the calculation results will be slightly smaller than the actual configuration, so take 6 groups should be enough to meet the demand of the backup time of load.

Can also calculate the car depot UPS system need DC 12 v / 100 ah models of battery four groups; Parking lot UPS system need DC 12 v / 100 ah models of battery 3 groups; Control center UPS system need DC 12 v / 100 ah models of battery 6 groups;

Combination of power operation mode of the system schematic diagram can understand and logical relationship.

1, the normal power supply operation

Two way power supply for two sets of UPS power supply, the main power supply 1 pick UPS1 main input, the main power supply meet UPS2 2 main input, two UPS bypass to main power supply at the same time on 1 or 2 main power (different sites can be different). Two sets of UPS output to the load side of STS switch at the same time, by setting the STS switch state, each brought about half load. This will ensure that the load on the two power supplies basic split, when two UPS are running in the bypass state, phase synchronization, the STS transformation are not affected.

UPS1 UPS2 and recharge the battery pack at the same time, the charging current 50% each. In order to convenient repair and maintenance in the future, each and every battery UPS is equipped with its own connection switch.

2, UPS fault operation mode

A, UPS2 fault, by STS will all of the load switch to UPS1, UPS2 and maintenance, repair and then restore the original load operation mode;

B, UPS1 fault, by STS will all of the load switch to UPS2 and then repair UPS1, repair and then restore the original load operation mode;

C, both set UPS fault, the static bypass through two UPS power supply to the load. At this point, the two UPS can be take to repair the bypass or closed for repair, after repair to the original load operation mode.

3, battery failure operation mode

Battery pack into 3-6 groups in parallel, if discover the battery failure or alarm, maintenance personnel to remove the fault battery group, maintenance of maintenance, repair the battery again after group back into operation.

4, loss of main power operation mode 1 road

A, UPS2 mains electricity, UPS2 stop output, through the STS cut all load to the UPS1;

B, UPS1 mains electricity, UPS2 stop output, cut to UPS2 by STS will all load.

5, lost 2 road mains operation mode

The two UPS to discharge the battery pack at the same time, through the STS after share the load. If any one UPS fault at this time, then the load will be through the STS transfer to another one UPS, battery will all transferred to the UPS use normal backup time is not affected.

Intelligent power distribution cabinet will combine the backup time requirements of the load, removal of the corresponding load on time.

6, maintenance operation mode

The single UPS a, overhaul, one is disconnected for repair, the other normal operation;

B, repair a single set of batteries, a group is disconnected for repair and other normal operation of the battery pack;

C, when two UPS maintenance at the same time, will play to the two UPS maintenance bypass or take turns to shut down for maintenance.

In summary, this scheme has the following features:

1, UPS power supply adopts centralized configuration, compared with distributed configuration, the scheme can more comprehensive utilization of UPS and battery resources, equipment reliability, save installation space, convenient maintenance and management, conform to the trend of the development of metro industry.

2, input power supply adopts double road power supply respectively at the same time, the ATS switch device for the front end, compared the scheme more saving investment, divide the load of dual power supply, and avoid the ATS of the single point of failure.

3, the system adopts two UPS double bus architecture, compared to the single and two parallel machine architecture, reduced the single point of failure, enhanced reliability.

4, adopts double battery pack machine sharing method, make sure that any one UPS failure, system overall backup time is not affected, and simultaneously has the following advantages:

Capital investment, saving to buy a battery, appropriate investment such as handling, installation also follow.

B, save installation space investment, appropriate investment such as decorate, modernize air conditioning configuration also follow.

C, save invest heavily in bearing.

D, save power consumption, maintenance operation cost investment, more environmentally friendly.

E, system expands more convenient, the host and the capacity of the battery pack can be separately, very safe, convenient and flexible use of funds.

F, maximize the battery efficiency, raise the utilization ratio of battery. Configuration scheme for traditional battery, larger quantity of battery power battery will discharge, small current battery capacity may not be put off many, grid has been restored. The shallow of small current discharge of battery is no good, over time the battery performance will drop, once a set UPS to fail, other UPS battery backup time will not meet requirements. Battery solution for sharing, because of the relatiely small number of cells, without power after the battery discharge current will be larger, battery capacity, also can put more conducive to improve the activity of the cells, extend battery life. Once a UPS broken, system backup time also will not be affected, for the battery failure and the failure will not follow UPS.

Five important degree, depending on the load, the use of time-sharing power supply mode, reasonable allocation of resources, to achieve maximum benefit.

6, in the NT series UPS, the product can meet the demand of rail transit plan, excellent product quality, factory service. Also used redundant communication line instead of LBS, save the investment, improve the efficiency, increased system reliability.